Liquid atomizers have a wide variety of applications. For curing diseases, typically a patient has to swallow pills or a medical worker injects liquid medicine into the patient. For the former, it is relatively simple but drug absorption needs a relatively long period of time (e.g., half hour or more). For the latter, the drug absorption time is short so that curing effect can be quickly seen. But the patient has to suffer the pain of needle injection on his/her body. As for medicine spray devices, they have advantages of the above both while without their disadvantages. Thus, medical spray devices have a bright future as agreed by most medical practitioners.
A conventional medicine spray device (e.g., atomizer) is used to shoot out a fine spray of medicine into the mouth of a patient. The nebular droplets then enter into the body of the patient for being absorbed through the lungs. However, the prior atomizers suffered from several disadvantages. For example, the spray of medicine is not acceptably fine, resulting in a poor absorption effect.
There are two types of medical atomizers commercially available. One is pressurized atomization type which requires a great pressure to atomize liquid medicine and thus consumes a lot of energy and generates noise. Moreover, the particle size of spray is an important factor in considering the buying of an atomizer by medical practitioners. Thus, the application of such type of medical atomizers is very limited because it can easily generate large particles in the spray.
The other type is mechanical vibration type which utilizes one or more piezoelectric elements to generate droplets. It is the dominant type of medical atomizer despite of drawbacks (e.g., high energy consumption, different sizes of the nebular particles, the installation of an additional fan, and bulkiness) thereof. For overcoming these drawbacks, piezoelectric elements and planar elements are incorporated into the mechanical vibration type of medical atomizer by some manufacturers. For example, U.S. Pat. No. 6,629,646 discloses a fluid ejection device as shown in FIGS. 1 and 2. The fluid ejection device comprises a cantilever beam 1 including a base portion affixed to a piezoelectric oscillator 2 and a free end provided with a planar surface 3 through which there are a plurality of microscopic tapered apertures 4. Fluid is in contact with the free end through which droplets are ejected from the aperture 4.
However, the patent still suffered from a couple of disadvantages. For example, the fixing of the piezoelectric oscillator 2 and the planar surface 3 on the beams 1 is hard to be secured, resulting in a shortened useful time and poor atomization effect. Moreover, a user has to replace all of the piezoelectric oscillator 2, the planar surface 3, and the beam 1 even if only either the piezoelectric oscillator 2 or the planar surface 3 is malfunctioned. This is not cost effective. Thus, continuing improvements in the exploitation of medical atomizers are constantly being sought.